Recent studies indicate that there may be a close relationship between the tissue long-chain acyl CoA esters (LCACAE)/carnitine ratio and heart function (dp/dt) during periods of anoxia, ischemia and reoxygenation. The apparent reason for this is that the LCACAE/carnitine ratio, by virtue of its effect upon adenine nucleotide translocator (ANT) and other key enzymes may regulate mitochondrial activity that, in turn, can effect the ability of the heart to recover from ischemia or anoxia. These findings support the idea that mitochondrial function plays a key role in the recovery from ischemia and indicate that respiratory ability of the ischemic myocardium may be controlled by a number of factors in addition to the oxygen supply. Current investigations indicate that the toxic effects of high fatty acid levels and sudden reoxygenation of the ischemic heart may also be related to the LCACAE/carnitine ratio. Investigations now underway will continue the study of the effects of the LCACAE/carnitine ratio upon metabolism in the ischemic and anoxic heart. Other current studies deal with the mechanism by which carnitine singly, or in combination with other agents, can protect the ischemic myocardium.